Motor drive device, refrigeration cycle apparatus, and refrigeration cycle system

Abstract

A motor drive device performs a feedback control of a motor based on a motor current that is a current flowing in the motor. The motor drive device includes: an index value calculation unit configured to calculate power or a work rate of the motor as an index value for use in determining whether an abnormality occurs in the motor or not based on the motor current and a control parameter used in the feedback control; a filter unit configured to perform a filtering process to extract an abnormal component by removing a component that is in a normal operating state, from the index value calculated by the index value calculation unit; and a diagnosis unit configured to conduct a diagnosis of the motor regarding an abnormality or degradation thereof based on the abnormal component of the index value.

1 . A motor drive device that performs a feedback control of a motor based on a motor current that is a current flowing in the motor, the motor drive device comprising:
 a controller configured to calculate power or a work rate of the motor as an index value for use in determining whether an abnormality occurs in the motor or not based on the motor current and a control parameter used in the feedback control, the controller including a filter configured to perform a filtering process to extract an abnormal component by removing a component that is in a normal operating state, from the calculated index value, the controller being configured to conduct a diagnosis of the motor regarding an abnormality or degradation thereof based on the abnormal component of the index value,   the filter including
 a low-pass filter configured to remove from the index value, a harmonic component based on a fundamental wave corresponding to a rotational frequency in a normal operating state of the motor, and 
 a high-pass filter configured to remove from the index value, a low frequency component in the normal operating state of the motor. 
   
     
     
         2 . The motor drive device of  claim 1 , wherein the controller is configured to
 integrate the abnormal component of the index value with respect to time, and   conduct the diagnosis of the motor regarding the abnormality or degradation thereof based on one or both of the abnormal component of the index value and an integral value that is a result of calculation by the integration.   
     
     
         3 . The motor drive device of  claim 1 , comprising an inverter configured to supply power to the motor,
 wherein the controller is configured to calculate an inner product of the motor current and a voltage command value, thereby calculating power of the motor, the voltage command value being the control parameter input to the inverter.   
     
     
         4 . The motor drive device of  claim 1 , comprising an inverter configured to supply power to the motor,
 wherein the controller is configured to   calculate an estimated value of torque of the motor, using a predetermined equation including the motor current,   calculate an estimated value of a rotation angle of the motor from the motor current and an amount of change in an estimated position of a rotor of the motor that is based on a voltage command value, and   calculate a product of the estimated value of the torque and the estimated value of the rotation angle, thereby calculating the work rate, the voltage command value being the control parameter input to the inverter.   
     
     
         5 . (canceled) 
     
     
         6 . The motor drive device of  claim 1 , wherein the filter is configured to remove from the index value, a component corresponding to a change in a speed command value for the motor. 
     
     
         7 . The motor drive device of  claim 1 , wherein
 a load of the motor is a compressor in which a rotational shaft of the motor is supported by a slide bearing, and   the controller is configured to output a result of the diagnosis to an external device.   
     
     
         8 . A refrigeration cycle apparatus comprising:
 a refrigerant circuit including a compressor in which a motor is provided; and   the motor drive device of  claim 1 , the motor drive device being configured to drive the motor.   
     
     
         9 . A refrigeration cycle system comprising:
 a refrigerant circuit including a compressor in which a motor is provided;   a power converter including an inverter configured to supply power to the motor; and   a controller configured to perform a feedback control of the motor through the inverter, based on a motor current that is a current flowing in the motor, and calculate power or a work rate of the motor as an index value for use in determining whether an abnormality occurs in the motor or not based on the motor current and a control parameter used in the feedback control,   wherein   the controller includes a filter configured to perform a filtering process to extract an abnormal component by removing a component in a normal operating state from the calculated index value, and the controller is configured to conduct a diagnosis of the motor regarding an abnormality or degradation thereof based on the abnormal component of the index value, and   the filter includes
 a low-pass filter configured to remove from the index value, a harmonic component based on a fundamental wave corresponding to a rotational frequency in a normal operating state of the motor, and 
 a high-pass filter configured to remove from the index value, a low frequency component in the normal operating state of the motor. 
   
     
     
         10 . The refrigeration cycle system of  claim 9 , comprising a display unit connected to the controller,
 wherein the controller is configured to determine whether a value of the abnormal component is greater than a predetermined abnormality determination threshold or not, and cause the display unit to display information indicating that an abnormality occurs in the motor or the motor is degraded, when the value of the abnormal component is greater than the abnormality determination threshold.   
     
     
         11 . The refrigeration cycle system of  claim 9 , comprising:
 a display unit connected to the controller,   wherein the controller is configured to   integrate the abnormal component of the index value with respect to time,   determine whether an amount of change in the integral value is larger than a predetermined second threshold or not, when an integral value that is a result of calculation performed by the integration is greater than a predetermined first threshold, and   cause the display unit to display information indicating that the amount of change is larger than the second threshold, when the amount of change is larger than the second threshold.   
     
     
         12 . The refrigeration cycle system of  claim 11 , wherein the controller is configured to reduce an upper limit of an operating frequency of the compressor, when the amount of change is larger than the second threshold. 
     
     
         13 . The motor drive device of  claim 1 , wherein
 a load of the motor is a compressor in which a rotational shaft of the motor is supported by a slide bearing,   the filter is configured to remove, using the low-pass filter, the harmonic component that is a pulsation component generated by gas compression in the compressor, from the index value, and remove, using the high-pass filter, the low frequency component that is a work component generated by a gas pressure in the compressor, from the index value, thereby extracting an abnormal torque generated by foreign material that enters a gap between a rotational portion and a stationary portion of the motor, and   the controller is configured to conduct the diagnosis of the motor regarding the abnormality or degradation thereof based on an abnormal power mount calculated from the abnormal torque.   
     
     
         14 . The refrigeration cycle system of  claim 9 , wherein
 the filter is configured to remove, using the low-pass filter, the harmonic component that is a pulsation component generated by gas compression in the compressor, from the index value, and remove, using the high-pass filter, the low frequency component that is a work component generated by a gas pressure in the compressor, from the index value, thereby extracting an abnormal torque generated by foreign material that enters a gap between a rotational portion and a stationary portion of the motor, and   the controller is configured to conduct the diagnosis of the motor regarding the abnormality or degradation thereof based on an abnormal power mount calculated from the abnormal torque.